1. Field of the Invention
This invention relates to an oil pump, and more particularly, to a manual/pneumatic dual-control oil pump which can operate manually or pneumatically.
2. Description of the Prior Art
A conventional jack assembly powered by hydraulic liquid generally comprises an oil pump and a cylinder. Those basic units are interconnected by hoses which sustain high liquid pressure. Accordingly, a complete and complicated hydraulic system is established. Because there are no directional limitations on the cylinder, the cylinder can be disposed on a steel truss in various orientations and can thus serve as a hydraulic puller, hydraulic bender, hydraulic fixer and hydraulic press.
Conventional oil pumps can be operated either manually or pneumatically. In the manual type, a lever is used to actuate the pump plunger. The operating mechanism is simple and the speed at which the plunger can be actuated is slow. Accordingly, a micro control can be carried out through the manual operation. In the pneumatically operated type, the speed at which the plunger is actuated too fast to control the operation of the pump accurately. In conclusion, both the manual and pneumatic operated oil pump have distinct advantages and drawbacks, respectively. Moreover, those two types of oil pumps cannot be used to replace each other.